/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: mirac
 * Date: 2025-07-19
 * Time: 23:31
 */
public class Main {
    public static void main(String[] args) {
        StringBuilder s1 = new StringBuilder("hello");
        s1.append(" world");  //hello world
        s1.append(123);       //hello world123
        s1.reverse();         //将字符串s1翻转
        String str = s1.toString();   //将StringBuilder ——> String
        System.out.println(str);
    }
}
